Health literacy is the degree to which an individual can obtain, process, and understand basic health information, which includes the ability to understand written questionnaires. Dementia screening tools are confounded with health literacy, but no means exists for correcting this test bias. Moreover, dementia- screening tools have not been validated for use by patients with low health literacy. Thus, screening may be inaccurate, leading to over- and under-diagnosis and in turn wasted resources on inappropriate care. A false- positive diagnosis is also extremely distressing for the patient. Thus, improvements in dementia screening are needed. Aims: This project aims to remove dementia-screening bias for people with low health literacy. We will determine differences in psychometric properties of dementia screening tools that are widely used in the clinical setting. We will also determine the independent contributions of age and health literacy to performance on dementia screening tools. Methods: We will recruit a large sample of participants across two primary care networks at separate institutions: Northwestern University and Boston University Medical Center. The sample will be evenly balanced across English versus Spanish language and adequate versus low health literacy. In addition to the sample from the parent grant, we will recruit an additional 160 older adults to ensure adequate representation across the lifespan. We will use state-of-the-art psychometric methods to determine differences among participants with low versus adequate health literacy, and whether these differences can be reduced by removing biased items from testing. We will also characterize the measurement approaches that are most prone to health literacy associated item bias. Impact: The impact of this proposal will be a precise understanding how health literacy influences dementia screening. Minimizing health-literacy- related barriers will make assessments in healthcare more accessible to people with low literacy. By improving screening accuracy, better medical decision-making will be enabled for individuals with dementia. This project has broad relevance: dementia-screening tools have not been validated for use with people who have low health literacy. We will present a generalizable approach that can improve screening procedures in both English and Spanish. Based on our analyses, we will also make specific recommendations of how to identify screening items that may be difficult for people with low health literacy.